1. Field of the Invention
The present invention relates to an insertion device for inserting a deformable intraocular lens into the eye. Examples of such a deformable intraocular lens include a deformable intraocular lens that is inserted into the eye in place of the natural lens when the latter is physically extracted because of cataracts, and a vision correction lens that is inserted into the eye for the sole purpose of vision correction.
2. Description of the Related Art
Implantation of an intraocular lens for treating cataract has been widely performed since 1949, when Ridley implanted for the first time an artificial lens; i.e., an intraocular lens, into the human eye in place of an opaqued natural lens during cataract surgery.
As disclosed in Japanese Patent Application Laid-Open (kokai) No. 58-146346, there have been invented improved intraocular lenses which can be inserted into the eye through a small incision formed in the eyeball. In one of the improved intraocular lenses, at least an optical portion is made of a deformable elastic material having a predetermined memory characteristic. In another improved intraocular lens, at least an optical portion is made of an elastic material having a predetermined memory characteristic, and there are provided supports which are made of a material different from that of the optical portion and are adapted to support the optical portion within the eye.
Moreover, as disclosed in Japanese Patent Application Laid-Open (kokai) Nos. 4-212350, 5-103803, 5-103808, 5-103809, and 7-23990, improved insertion tools have been proposed. By use of these tools, the optical portion of an intraocular lens is compressed, rolled, bent, stretched, or folded so as to reduce its exterior size, thereby enabling the intraocular lens to be inserted into the eye through a small incision formed in the eyeball. These insertion tools facilitate an operation for implanting an intraocular lens into the eye.
FIG. 3 and FIGS. 4A and 4B show the conventional deformable intraocular lenses. The deformable intraocular lens 1 shown in FIG. 3 is composed of a circular optical portion 2 and two symmetrically disposed supports 3. The circular optical portion 2 is made of an elastic material having predetermined memory characteristics. The supports 3 are made of a material different from that of the optical portion 2, and bases 3a of the supports 3 are embedded in the peripheral region of the optical portion 2 for fixing, while wire-shaped tails 3b of the supports are curved. The deformable intraocular lens 1 shown FIGS. 4A and 4B is composed of a circular optical portion 2 and a pair of thin plate-shaped support portions 4 that are integral with the optical portion 2. The optical portion 2, like the optical portion 2 shown in FIG. 3, is made of an elastic material having predetermined memory characteristics. The support portions 4 are projected from the periphery of the optical port 2 in opposite directions.
These intraocular lenses 1 are inserted into the eye by use of an insertion device as shown in FIG. 5. The deformable intraocular lens 1 is folded in order to reduce its exterior size and is advanced along an insertion tube in order to be inserted into the eye through an incision formed in the eyeball.
FIG. 5 is a partially cutaway overall perspective view of a conventional insertion device for inserting a deformable intraocular lens.
In FIG. 5, reference numeral 11 denotes the insertion device; 12 denotes a device body; 13 denotes a screw sleeve; 14 denotes a push rod; 15 denotes an enclosing member having a lens receiving section and an open/close mechanism and adapted to deform a deformable intraocular lens into a smaller size; 16 denotes a slide stopper which engages the open/close mechanism so as to maintain the open/close mechanism in a closed state; and 17 denotes an insertion tube.
When the insertion device 11 is used to insert a deformable intraocular lens 1 into the eye through a small incision, the open/close mechanism of the enclosing member 15 of the insertion device 11 is first opened. Subsequently, the deformable intraocular lens 1 is placed on the lens receiving section, and the open/close mechanism is closed so as to reduce the exterior size of the deformable intraocular lens 1. Subsequently, the slide stopper 16 attached to the device body 12 is moved toward the lens receiving section so as to engage the open/close mechanism and bring the same into a closed state. Thus, placement of the intraocular lens 1 into the lens receiving section is completed.
Subsequently, the screw sleeve 13, disposed at the rear of the device body 12, is moved toward the device body 12, brought into engagement with a screw portion 12b formed on the device body 12, and rotated in order to advance the push rod 14, to thereby push forward the deformable intraocular lens 1 from the lens receiving section. As a result, the deformable intraocular lens 1 is inserted into the eye through the tip end of an insertion tube 17 provided at the front end of the lens receiving section, which tip end has been inserted into the eye through a small incision formed in the eyeball.
Japanese Kohyo (PCT) Patent Publication No. 11-510711 discloses another conventional insertion device. In this insertion device, an intraocular lens is advanced within an insertion tube by mean of advancing movement of a push rod caused by an operation of pushing a plunger.
In the conventional insertion device shown in FIG. 5, when an operator wishes to advance an intraocular lens within the insertion tube, the operator must rotate the screw sleeve with one hand in order to advance the push rod, while holding the device body with the other hand. That is, the operator must use both hands to operate the insertion device in the course of an operation during which the operator must use various operation tools. Therefore, the necessity of using both hands hinders the ease of use during the operation.
In the conventional insertion device in which the push rod is advanced through an operation of pushing a plunger, since a pressing force is applied to the plunger along a straight direction, performing fine adjustment in relation to advancing movement of the push rod requires a great deal of skill.
An object of the present invention is to provide an insertion device for a deformable intraocular lens, which device allows an operator to use a single hand or both hands for operation of pushing an intraocular lens into the eye.
In order to achieve the above object, the present invention provides an insertion device for deforming a deformable intraocular lens into a smaller size and inserting the intraocular lens into the eye, comprising a device body; an insertion tube attached to a front end of the device body and adapted to be inserted into the eye; a push rod axially movable through the device body and the insertion tube and adapted to insert the intraocular lens into the eye when advanced; a drive member rotatably provided at a rear end of the push rod; a motion conversion mechanism disposed between the device body and the drive member and adapted to axially move the drive member, upon rotation of the drive member, in order to axially move the push rod; and a push member provided at the rear end of the push rod and projecting rearward from the drive member. Preferably, the motion conversion mechanism includes a male screw formed on a rear end portion of the device body and a female screw formed on the drive member and in screw engagement with the male screw.
By virtue of the structure as described above, the operation of inserting an intraocular lens into the eye can be performed by use of a single hand or both hands. That is, one-hand operation or two-hand operation can be selectively used in accordance with the conditions of the operation. Therefore, ease of operation of the insertion device can be improved.
Preferably, the device body includes adjustment means for adjusting resisting force against the axial movement of the push rod. More preferably, the adjustment means is an elastic member which generates frictional resistance.
In this case, the force required to insert an intraocular lens can be adjusted to a desired level, thereby providing operation feeling suitable for surgery which requires delicate operations.